240 CLASS IV. 



ALCYONIUM. 



PoLYPiDOMS of various shapes, having the appear- 

 ance of a thick, porous, or cellular mass, spread out or 

 ramified, sometimes lobed, and at others in the form 

 of a crust ; the interior substance spongy or corky, 

 surrounded by a radiated, tubulous tegument, and en- 

 closed in a hard leathery rind. 



The cells of this Polypidom are round, and une- 

 qual in their diameters, from four to five milleme- 

 tres in depth, separated from each other by thin 

 partitions, which are rendered opaque by a vast 

 quantity of solid globules, that appear to form the 

 least animated part of the zoophyte. These cells en- 

 close a polypus, externally composed of a transparent 

 sack or membrane ; which is fortified by eight fili- 

 form longitudinal fibrous bands, placed at equal dis- 

 tances, and difiicult to be perceived owing to the 

 presence of numerous transverse and parallel fibres. 

 The longitudinal fibres seem attached to the bor- 

 ders of the cells, and to the roots of the tentacula. 

 The sack (which is capable of extending and con- 

 tracting, the upper part falling back when the little 

 animal retires within its transparent covering) en- 

 closes the body of the polypus, having in the centre 

 a hemispheric mass, divided into eight equal parts 

 by vertical partitions, whose summits present a 

 round or lozenge-shaped opening, at the will of the 



